Class 12 Chemistry Aldehydes Ketones Acids Physical Properties of Carboxylic Acids

Physical properties

  1.  Existence: They are Colourless liquids with pungent smell. The higher members are oily liquids and still higher members are waxy solids.
  2. Solubility : First four members are soluble in H2O that is-  HCOOH , CH3 , COOH , C2H5 COOH , C3H7 But as number of Carbon atoms increase , solubility decrease because  size of non-polar group increases. Solubility of smaller  members is due to formation of Hydrogen bonds.
  3. Boiling points:Boiling points are higher due to formation of hydrogen bonds . As number of Carbon atoms increases , boiling point also increases.


  1. Melting point : Show un-usual behaviour.
  • Those having odd number of carbon atoms possess low Melting point -
  • CH3 CH2 COOH  =  251k
  • High Melting point of members with even number of Carbon atoms –
  • CH3 CH2 CH2 COOH   =   367k
  • It is due to symmetrical structure.



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